In the Hindu mythology, at the top sits an trinity consisting of Brahama, Visnu and Siva or Mahesh. They are responsible for running the whole universe. Visnu is the source of universe and of all things. He sleeps in the primeval ocean on the thousand headed snake Shesha. In his sleep a lotus grows from his navel and in this lotus the demiurge Brahma is born who creates the world. Once the creation of the world is over, Visnu awakes to reign in the highest heaven called Vaikuntha.
Visnu has the dark blue color and four arms and in his four hands he bears his emblems namely conch, discus, mace and lotus. His mount is a great eagle Garuda which is generally shown as half human face. His spouse is Lakshmi who is also a paramount Goddess in her own right.
He is always smiling and benevolent in contrast to Siva who has some fierce traits. He incarnates himself wholly or partially from time to time. We already know about his incarnations or Avatars as :
1.The Fish : Matsya
2. The Tortoise: Kurma
3. The Boar : Varaha
4. The Man-lion: Narasimha
5. The Dwarf : Vamana
6. Parasurama : Rama with Axe
The role has been played in all 9 avatars already. Now in Kaliyuga, to set the things right, to put the people on the path of righteousness and destroy the corrupt, Kalkin is awaited. It is said that in this Avatar he will appear as a man riding a white horse with a flaming sword in his hand and by eliminated all the vices, he will restore the age of Gold.
Incidentally, a Bollywood movie with the name Shahenshah featuring Amitabh Bachchan was based loosely on the theme of coming of Kalkin. With this film, Amitabh made a comeback after recovering from the fatal injury and the hype created by Tinnu Anand, the maker of the movie, helped the movie to become hit a the box office.